1. Field of the Invention
The present invention relates to a door operator, in particular to a door operator comprising a locking mechanism with a bidirectional rotary block.
2. Description of the Prior Art
FIG. 1 shows a locking mechanism having a chain disk for a manual door operator disclosed in U.S. Pat. No. 8,915,287 issued to the Applicant. The locking mechanism comprises a wedge wheel (36′) fixedly connected to a drive shaft (37′) and accommodated in a ring socket (34′). The wedge wheel (36′) includes a plurality of axial slots (361′) each having two bottom surfaces (362′) and two side walls (364′). Each of the bottom surfaces (362′) has a first end portion (P1′) and a second end portion (P2′). The first end portion (P1′) is spaced from the inner wall of the ring socket (34′) by a first distance (D1′). The second end portion (P2′) is spaced from the inner wall of the ring socket (34′) by a second distance (D2′). The first distance (D1′) is smaller than the second distance (D2′). A plurality of fixed posts (351′) are axially received in the axial slots (361′) and located at the bottom surface (362′). Each movable post (365′) has a diameter greater than the first distance (D1′) and smaller than the second distance (D2′). Each fixed posts (351′) has a diameter smaller than the first distance (D1′). A plurality of compression springs (366′) are positioned on the side wall (364′) and urge against the plurality of movable posts (365′) to move them away from the side wall (364′).
When the chain disk rotates, the plurality of fixed posts (351′) urge against the plurality of movable posts (365′), so that the wedge wheel (36′) is driven to rotate the drive shaft (37′), thereby rolling up or dropping down the rolling door. When the chain disk stops rotating, the movable posts (365′) are locked by the wedge wheel (36′), so that the drive shaft (37′) is not rotatable, thereby stops the operation of the rolling door. The manual door operator omits the conventional clutch device, and thus it is simple in construction, compact in size, easy to operate and low in cost.
Further, FIGS. 2 and 2a illustrate U.S. Pat. No. 8,657,096 issued to the Applicant, which discloses an electric door operator having a chain disk locking mechanism. The door operator includes an electric motor, and a chain disk locking mechanism (4′). The drive shaft of the motor is axially connected to a stationary shaft (41′), and the chain disk locking mechanism is connected with the stationary shaft (41′). The chain disk locking mechanism (4′) comprises a chain disk (42′) having a central circular bore (421′), a plurality of fixed pins (422′) axially located in the central circular bore (421′), an engaging rotary block (43′) located in the central circular bore (421′), and comprises a number of axial slots (431′) that correspond to the plurality of fixed pins (422′). Each axial slot (431′) includes a first end face (4311′) and two second end faces (4312′). The two second end faces (4312′) are disposed respectively on both sides of the first end faces (4311′). The first end face (4311′) and an inner wall (4210′) of the central circular bore (421′) are spaced apart by a first radial gap (D1′). The second end face (4312′) and the inner wall (4210′) of the central circular bore (421′) are spaced apart by a second radial gap (D2′). The first radial gap (D1′) is narrower than the second radial gap (D2′).
A plurality of moving pins (5′) are received within the axial slots (431′), and are located between the second end faces (4312′) and the center circular bores (421′). The diameter (R′) of each movable pin is greater than the first radial gap (D1′), and less than the second gap (D2′). The diameter (r′) of each fixed pins (422′) is less than the first gap (D1′). Each axial slot (431′) comprises two end walls (4313′), which is disposed at both sides of the axial slot (431′), and adjacent to the two second end faces (4312′). Each end wall (4313′) is provided with a compression spring (51′) which urges against the plurality of moving pins (5′) to move the pins away from the end wall.
When the chain disk (42′) is pulled to rotate, the fixed pins (422′) press the moving pins (5′) so as to push the engaging rotary block (43′) to rotate with the stationary shaft (41′) together. When the stationary shaft (41′) intends to rotate, the first end faces (4311′) of the engaging rotary block (43′) and the inner wall of the central circular bore (421′) block the moving pins (5), and prohibits the stationary shaft (41′) from rotating.
However, the above engaging rotary block has the following disadvantages in manufacture and use:                (1) Since the engaging rotary block includes axial slots having planar, included angles, the chain disk tends to slip at the initial pull. That is to say, the engaging rotary block has a relatively weak torsional strength, and thus is not suitable to be used on a big rolling door.        (2) The axial slot is trapezoidal in shape, and thus has a large diameter, and needs a special machine for machining. As such, the manufacturing is time-consuming and expensive.        (3) The axial slot is complicated, and thus requires high precision in machining, and the defective rate of the product is high.        